Spengler served 17 years in New York State prison on manslaughter charges, police officials said. He was on probation until 2006 and reportedly had lived quietly with his mother, who died in October, and sister at 191 Lake Road, along a sliver of land between Irondequoit Bay and the lake.

Spengler's 67-year-old sister, Cheryl, remains unaccounted for.

Spengler apparently set fire to the home and a vehicle to lure firefighters, whom he shot from a berm nearby. Police have have not determined a motive for the arson and killings, nor have they released details about the weapons Spengler used or possessed. As a convicted felon, he could not legally own firearms.

Police Chief Gerald Pickering, choking up frequently as he spoke to reporters, said all four firefighters who responded to the call at 5:35 a.m. ET came under fire when they drove up.

The dead are Webster Police Lt. Mike Chiapperini, 43, a volunteer firefighter and the police department's public information officer, and Tomasz Kaczowka, 19, who worked as a 911 dispatcher for Monroe County. Chiapperini was named "Firefighter of the Year" two weeks ago.

"It is a very difficult situation," Pickering said, his voice quavering.

"People get up in the middle of the night to fight fires," he said. "They don't expect to be shot and killed."

He said Chiapperini "took public service to the nth degree. He was all about giving back to the community. When he wasn't working as a police officer he was always the first on the truck."

Kaczowka, who joined the 125-volunteer West Webster Fire Department a year ago, was substituting for older members so they could be home with their families for Christmas.

"He didn't have to be there," said Al Sienkiewicz, a former chief and department now spokesman. "He was bunking in voluntarily so others could stay at home."

The 911 center's director said he was ""everyone's little brother" and would often bring desserts his mother made.

The injured firefighters are Joseph Hofsetter and Theodore Scardino. Hofsetter suffered a severe injury to his pelvis. Scardino was shot in the left shoulder, with the bullet hitting his lung. An off-duty police officer who was driving by at the time also was injured by flying shrapnel.

Pickering said Spengler had staked out a position with an arsenal of several firearms on a berm overlooking the scene.

"It appears that it was a trap," Pickering said. "There was a car in a house that was engulfed in flames, probably set by Mr. Spengler, who lay in wait with his armaments and shot the first responders."

"Looking at his history, obviously this is an individual who has a lot of problems, who killed his grandmother, and I'm sure there were mental health issues," Pickering said.

Spengler told police he hit his grandmother, Rose Spengler, with a hammer during an argument. He then went home and told his mother, who found her body at the bottom of the basement stairs. He also reportedly talked about suicide after confessing to a detective.

As his trial for second-degree murder was beginning in July 1981, Spengler pleaded guilty to manslaughter, telling the judge he wanted to spare his family "the pain of a trial."

Pickering said the 911 call early Monday was apparently called in by a resident in the neighborhood of small lakeside vacation homes.

At West Webster Fire Department, the flag outside was lowered to half-staff.

"These firemen are part of our family. You go into a fire with these guys. To see them go down with something like this is totally unexpected. We are in shock," said fire district commissioner Billy Gross.

Gov. Andrew Cuomo said the State Police and Office of Emergency Management were working with local authorities.

"Volunteer firefighters and police officers were injured, and two were taken from us as they once again answered the call of duty," Cuomo said in a statement. "We as the community of New York mourn their loss as now two more families must spend the holidays without their loved ones."

Harold Schaitberger, president of the International Association of Fire Fighters, issued a statement calling the calculated shooting of firefighters "both senseless and cruel."

"The firefighters who responded today were performing a selfless, meaningful service to their community, unaware that a cold-hearted maniac was planning to ambush them and take their lives," the statement said. "Coming on the heels of the horrific tragedy in Newtown, Connecticut, and on Christmas Eve, this shooting is even harder to comprehend."

Webster resident Michael Damico was among those neighbors who were evacuated.

"The whole strip's been evacuated," he said. "They're evacuating all of the houses and going through them."

Damico's son woke him up around 8 a.m. to tell him about the fire that was burning down the street.

"We looked out the window and we saw the SWAT team and everyone around," he said.

"Some people on this bus already watched their houses burn," Damico said. "They're not happy."

The village of Webster, with a population of about 5,000, is located in the center of the town of Webster, where more than 42,000 people live northeast of Rochester, along Lake Ontario.

Firefighter shootings over the years

Instances of firefighters shot and killed while responding to a fire or other emergency incident are relatively rare.

A gunman in 2008 killed firefighter Ryan Hummert, 22, and wounded two police officers as they responded to a pickup truck and house fire in Maplewood, a St. Louis suburb. Later that year, a carjacker shot and killed off-duty St. Louis firefighter Leonard Riggins, who saw a car wreck and stopped to help, not knowing that the armed carjacker had crashed the car.

Roswell, N.M., Fire Chief Steven Jones, 46, died in March 2002, after responding to a structure fire. As Jones approached the house, a man began firing, hitting Jones in the head and killing a paramedic. The shooter, a man with a history of mental illness, had set the fire, killed a neighbor, shot the neighbor's 3-year-old son and took a 5-year-old child hostage, before killing himself, according to a report from the Roswell Fire Department.